xml-dev - Re: Are entities containing mark-up allowed in attribute values?

[Rick JELLIFFE <ricko@geotempo.com>]

> Rob Lugt got a number of answers to his question:
> 
> >Are entities containing mark-up allowed in attribute values?
 
An attribute value cannot contain elements. So if I have
 <x y="&lt;z/&gt;" />
then the contents of z (i.e. <z/> ) are not interpreted as 
some kind of empty-element tag.   If I have
 <x y="<z/>" />
it is an error.

An attribute can refer to an element or entity which does contain
markup of element (i.e., IDREF or ENTITY attributes) and an
attribute can contain text which some later, extra-XML process
parses as XML. 

At different points in an XML document, different kinds of
markup are recognised or allowed. To keep this under control,
in XML you can only type < or & if you are using them 
  * as part of an open delimiter
  * inside a CDATA sections, PI or comment

Cheers
Rick Jelliffe